Column A: it was filled with a mixture of functionalised pro-
MWCNTs and inert microparticles of Epolene® (Eastman Chemical
Products, Inc., Kingsport, TN, USA), a low-density polyethylene wax
that offers good high-temperature stability, low-temperature flexibility,and very good compatibility with the use of mineral acids. The amount
of eachmaterialwas: ~1.0 mg of pro-MWCNTs and 10mg of Epolene®.
Column B: this column was filled with a mixture of NPC and inert
microparticles of Epolene® but using different proportions (~1.0 mg
of NPC and 5.0 mg of Epolene®).
The dry packing method was employed for the preparation of both
microcolumns. Then, theywere connected to the systemwith PTFE tubing
to form the preconcentration system. Microcolumns A and B were
preconditioned by the blank solution prior to each cycle.
The sorbents resulted stable over a wide range of pH and the columns
packed with both sorbent materials had a lifetime of (at least)
600 cycles of Sb(III) retention/elution without demand for generation
or modification of the initial conditions.